It is often desirable in textile yarn handling and weaving operations to be able to readily identify particular yarns. For example, when a loom beam of yarns is made up of various yarns of different sizes or fiber types, applying distinguishing coloration to the composite yarns allows the beam to be readily inspected and further allows yarn "piece up" to be quickly accomplished in the event a particular yarn breaks during weaving. This coloration must be easily removable, however, so that it does not interfere with permanent dyeing.
In the past, this temporary coloration typically has been accomplished by directing the yarns through a bath containing a fugitive tint carried in a liquid transfer medium such as water. The yarns would take up and absorb the liquid along with the tint and thereafter be squeezed by rollers to remove a portion of the excess liquid. The yarns then had to be subjected to heat to fully remove the remaining liquid prior to weaving or other yarn handling.
This tinting was typically carried out on modified slasher apparatus which included a tint bath and drying means. Tinting could be so accomplished on the slasher even if the slasher was not being utilized to apply sizing composition. Tinting in this manner, however, presented several problems.
First of all, the yarns run through the bath retained a substantial amount of excess liquid that required a corresponding substantial amount of energy to heat and remove the undesired liquid. The amount of this wet pickup was about 70% to about 75% by weight. Furthermore, the yarns were so saturated by the tint bath that the tint penetrated into the yarn as well as coloring the exterior so that eventual tint removal prior to dyeing was made undesirably difficult.
In addition, applying tint utilizing slashing apparatus in this manner was relatively slow, at a yarn travel rate of only about 80 yards per minute, even when sizing was not being applied. This slow speed was necessary in order to carry out the drying required. And subjecting the yarn to this additional process and handling allowed the introduction of defects that would otherwise have been avoided. Finally, this bath form of tinting did not make the most effective use of the available tint since quantities of tint were lost and exhausted in the handling of the tint liquid.
Efforts were made by some yarn manufacturers at tinting yarns during the manufacture thereof and supplying them in tinted form to fabric manufacturers but the efforts have not been satisfactory. The yarns so produced have been limited in coloration and the tinting itself has been spotty and nonuniform.